Mate-choice copying in sailfin molly females: public information use from long-distance interactions

Animals may use public information gained by observing sexual interactions between conspecifics and use this information for their own mate choice. This strategy, called mate-choice copying, is considered to play an important role for the evolution of mate preferences. Mate-choice copying is defined as non-independent mate choice, in which a female's probability of choosing a given male increases if other females have chosen that male previously. Using the livebearing sailfin molly (Poecilia latipinna), we asked if increasing the distance between a model female and a male would affect copying behaviour of focal females. We tested focal females in two different treatments: (1) model female and male in close proximity and able to interact at close range and (2) model female and male positioned apart from each other and restricted from close-range interactions. We could show that focal females copied the choice of a model at short distance to the prior non-preferred male as predicted from previous experiments. Surprisingly, focal females also copied the choice of a model when positioned 40 cm apart from the male. When no model female and, hence, no public information were provided (choice consistency control), focal females were consistent in their mate choice, indicating that changes in mate preference observed in the two treatments were due to the simulated mate choice of the model female. Our results demonstrate that females gain and use public information and copy the mate choice of other females even when heterosexual conspecifics interact from a distance. Significance statement Animals can copy the mate choice of conspecifics by observing their sexual interactions and, hence, choose the same mate as the other individual did before. So far, mate-choice copying was investigated when the so-called model female and the male were in close proximity. Here, we investigated whether female sailfin mollies (Poecilia latipinna) copy the choice of a model female for a male when the model female can only interact with a male at distance. We show for the first time that even interactions of heterosexual conspecifics at distance provide public information for an observing focal female to copy the choice of the model. Our results imply an even wider information transfer in sailfin molly social networks than previously thought.